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Black soot, Running Rich, No power under load

16K views 9 replies 5 participants last post by  moparpower1992 
#1 ·
Alright gentlemen, My wife has a 1999 Doddge Durango SLT, 5.9L 4x4. Its been a great vehicle until a couple weeks ago.

She stated she was driving my son to daycare, and the vehicle started sputtering. She said she went to hit the gas and it did nothing. just putted along then it just kicked up and drove. The issue went away for a couple days but it came back. I get home from work and I take a look to see if i can pin point the issue. Ive done some browsing around on this site, along with the NAGCA forums (as i have a grand cherokee with the 5.9L).. After reading quite a few threads and mixed emotions i cannot figure out.

the issues
1. Running Extremely rich - Getting about 3 mpg
so rich that if i stand behind the vehicle my eyes start to burn because of the gas fumes.

2. Black Soot blows out of the exhaust about every 3-5 seconds. Looks like black snow.

3. There is no power under load. I can put it in D, hold the brake and apply the gas and it will not exceed past 2000 rpm, it doesnt even have enough power to move. (it used to spin the factory 31x10.5x15 tires with ease)

4. It will occasionally start to stall out just driving.. hasnt happened to me yet. but has happened to my wife

the only code it throws is an Pre Cat O2 sensor. which i have yet to replace. (will be doing so tomorrow)

At idle it runs wonderfully, no sputters, no misfires, no back fires, revs all the way throught the tach..

I have replaced the TPS, cleaned the IAC, New sparkplugs, wires, cap, rotor. Just minor tune up within the past 5 months. It has recieved oil changes religiously. Trans has been recently serviced as well. The cooling system has been replaced (waterpumpt, tstat, radiator as well)

there are NO leaks in this vehicle at all

There is no knocking, no ticking, no odd sounds what soever coming from the engine. Nor is there grinding or binding coming from the rear diff. the brakes work great, the entire brake system has been replaced 6months ago.. rotors calipers drums, lines, ect.

I have come to the conclusion that it may be the O2 sensor, or a clogged cat but any help or suggestions would be greatly appreciated.

thanks. I will keep this post updated until i figure out the issue
 
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#3 ·
I'm betting on a bad O2. I've had both clogged cats and bad O2s, with the clogged cats, you lose power, but you're not blowing black smoke. Bad O2s, smoking like a diesel, no power and horrible gas mileage. Altho, depending on how long you've driven it like this, it could have clogged the cats as well. Fix the O2 first and go from there. :eek:nethumb:
 
#4 ·
The cats are clogged now anyway, changing the O2's out will not change anything. He never said anything about the amount of miles he ran it with the problem but anything more than a mile and at speeds above 35 mph will ruin the cat. I foudn this out the hard way on my Neon when I first put on MSD wires and a coil(had the ones for the SRT-4 2.4 instead of the 2.0) and it ran poorly for about 10 miles before I pulled off and called AAA.
A few weeks later, I started having a CEL pop up for a bad pre-cat sensor, so I replaced that and it lasted a day before it came back. I later went to the dealer and their test showed I had a clogged cat. Don't assume the cat won't be plugged even driving in that condition the OP did for even a short distance.
 
#6 ·
alright, i went out and bought some new sparkplugs, just to replace them. I pulled the old ones out and they were just all black. no oild deposits on them. just looked like some carbon deposits. I also replaced the pre cat O2 sensor. Reset the computer and let it run for about 20 mins.

it doesnt seem to run as rich now, nor do i see any black soot coming out of the exhaust. I took it for a test drive. just a few miles. It seems my mpg went up. I went to find a bunch of hills to drive up.. drove up all of them no issues at all.

BUT..... when i just sit in my drive way at a stop, in D. And i hold the brake down.. Brake torque it, it just goes to about 2k rpm and sits there. Maybe i just have that good of brakes.. who knows..

Im gonna take it to an exhaust shop tomorrow to see if the Cat is clogged.. If so, Im just going to have them cut it off and have them put a new exhaust system on there..


other than that it seems to be fine.. i guess ill find out here in the next week or so
 
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